IanAnd wrote:Many people talk about experiencing a "kind of headache" sensation or "pressure in the head" sensation.
Nowadays this is exactly what I'm experiencing. And it's almost always there, when I'm travelling, reading, writing, in the toilet, almost asleep during a boring lecture, the list goes on... and I'm pretty sure that I'm nowhere near "deep levels" of concentration. This is just my opinion, of course, but I'd say these are pretty common and one should actually try to be indifferent to these deceptions of the mind.
I get something similar, and I'm also quite sure it has nothing to do with nimitta or jhana. It's explained in different ways depending on who you ask: energy blockage that will clear out with time, too much effort, wrong concentration, etc. Of course, in Ian's case it might be the real thing, I don't know.
Either way, jhana/nimitta subject is very tricky - different people say different things, and that leads to doubt, which is one of the five hindrances that make samatha difficult. That's why the advice is often given to pick one particular method/school of thought (the best would be if you have a teacher that you can ask directly about your problems) and stick to it.
Though, I think it's good to do a little research beforehand. For example, according to abhidhamma and commentary, some meditation subjects do not produce a nimitta (counterpart sign) at all. Or in case of the breath - it is considered to be a very hard meditation object. One reason is that it starts to disappear as concentration gets stronger, etc. Another reason I think is that there are so many aspects of breath that might be taken up as the object of meditation, thus leading to confusion. For example it can be taken up as earth element (hardness/softness of touch at the nostrils, or lips), as air element (pressure), as fire element (is it warm or cold) and then there are many conceptual attributes of the breath that can be taken up simply as mental objects (calm, heavy, smooth, etc). And I'd guess that nimitta would likewise differ depending on the object.
So, maybe kasina practice might be simpler because it can produce a nimitta of one kind only, which will be a replica of the kasina itself, so there'll be no confusion about it. Or if you don't like nimittas, then you might choose brahma viharas as meditation objects, as they do not produce a nimitta (counterpart sign), but still allow jhana entry (some meditation subjects like 10 recollections, or four elements do not produce nimitta, but they do not allow jhana entry either - for a quick summary on this you can check ACMA
table 9.1 on pages 334-5, and the whole chapter IX is a great summary of samatha and vipassana meditation according to abhidhamma and commentary, for much more detail check out Visuddhimagga) .